As if mom were not to blame for enough already, new research is showing a link between early puberty in girls and a lack of maternal-infant bonding.

That puberty is transforming girls into women at increasingly earlier ages is hardly new; just last month, a study in Pediatrics showed that some girls are starting to show signs of puberty by age 7. Why it’s happening, though, is apparently up for debate. It’s often attributed to environmental toxins, estrogens in plastics, other chemicals and food and to poor diet, which can lead to obesity.

But in a rather unusual way of looking at things, researcher Jay Belsky of Birkbeck University in London hypothesized that precocious puberty may be a result of a risky, unstable environment — for example, one typified by weak infant-parent bonds. According to evolution, a girl’s perception of such an unstable environment could compel her to want to reproduce before she’d die. You following this so far? (More on Time.com: Another Cause of Early Puberty in Girls: Absent Dads)

“An evolutionary biology perspective says, ‘look, the thing that nature most cares about — with respect to all living things, humans included — is dispersing genes in future generations,'” says Belsky, whose research is published in Psychological Science. “Thus, under those conditions in which the future appears precarious, where I might not even survive long enough to breed tomorrow, then I should mature earlier so I can mate earlier before that precarious future might get me.”

To test his hunch that early puberty tracks insecure attachment between mom and baby, Belsky crunched numbers on 373 girls who were followed from birth until their 15th birthday as part of a National Institute of Child Health and Human Development study on early child development. Researchers assessed how attached the babies were to their mothers at 15 months by separating and reuniting them. Babies who smiled, cooed and otherwise seemed super-happy to see their moms were deemed secure; those who cringed or didn’t take comfort in their return were labeled insecure.

To detect when puberty took root, medical professionals evaluated the girls annually starting at age 9½. They found that formerly insecure babies hit puberty two to four months sooner than secure babies and got their periods earlier too.

But is it really a matter of security vs. insecurity? Or might the underlying culprit actually be stress? “If there’s a lot of family stress, it could lead to impaired bonding, or maybe impaired bonding is leading to family stress,” says Frank Biro, director of adolescent medicine at Cincinnati Children’s Hospital and author of a recent study in Pediatrics that found that some girls are starting to show signs of puberty by age 7. “We know that higher degrees of family stress can lead to early puberty.” (More on Time.com: Better-Nourished Babies Grow Up to Be Haler, Heartier Don Juans)

In any case, moms, you can relax: Your inattentiveness to your daughters when they were teeny-tiny is not the only thing that makes them sprout breasts early. Environmental chemicals and genetics can’t be ignored, acknowledge the researchers. Better nutrition may play a role. Oh, and there’s a documented 150-year-old trend of girls maturing earlier.